In 2008, Cornell psychologist David Pizarro tried to explain just how we interact with that fear. He and his colleagues had surveyed subjects about their political beliefs and then asked each how much he or she would be disgusted by the smell of urine, the sight of crawling maggots, or the knowledge that a bowl of soup had been stirred by a used flyswatter. People develop their gag reflexes long before they pick a political movement, Pizarro speculated, and many of the political debates that appear to be moral tests for adults eventually reveal themselves as little more than a measurement of childlike revulsion. Does prisoner torture or the sight of two men kissing or the nihilistic gore of Grand Theft Auto make you gag?
Those on the right were the most easily grossed out, Pizarro found, confirming our intuitive picture of live-and-let-live liberals and law-and-order conservatives. But research also showed that conservatives were not only turned off by flies, turds, and images of people fighting but that they were positively turned on by their own feelings of repugnance, especially in a related experiment conducted at the University of Nebraska–Lincoln. Researchers there outfitted subjects with an eye-tracker, which measured how and where participants focused their attention, before projecting collages mixing images that are known to trigger adverse reactions (spider, more maggots) and those that stimulate goodwill (cute rabbit, happy child). Unlike liberals’ eyes, conservatives’ eyes dwelled unusually long on images they found most repellent. Similarly, when researchers used electrodes to measure the amount of moisture released by subjects—a typical method of ascertaining emotional response—they found that conservatives were more aroused by images of politicians they disliked (the Clintons) than those they liked (Ronald Reagan, George W. Bush). Liberals were excited by the sight of those they liked.
In Man Is by Nature a Political Animal, published last year, the anthology’s editors argue that any open-minded pursuit of these questions will show that evolutionary impulses shape our political inner lives as much as our physical form. McDermott, one of the volume’s editors, predicts that within ten years saliva swabs will identify a genetic link explaining why some individuals welcome immigration while others respond violently to it. Citizens with “really strong immune systems are going to be all right with immigration,” McDermott ventures, because they’ll be less concerned with the pathogen threat that outsiders pose.
“It’s hard to find something we haven’t been able to say is significantly affected by the heritability of genes,” says James Fowler, a UC–San Diego social scientist. If genes can make someone more prone to depression or bad temper, why couldn’t they also explain his political views? And if genes were shaped over time by evolutionary pressures that drove people to protect their turf or successfully reproduce, why shouldn’t we see politics at least partly in the same terms?
“I know there’s a knee-jerk reaction that this can’t be right: ‘There’s no way there’s a gene that’s responsible for my politics,’ ” says Matthew C. Keller, a behavioral geneticist at the University of Colorado. “For me, this is a genetic IQ test. If they say that type of thing, it means they don’t understand genetics that well.”
To those immersed in the science, moral concerns have seemed to exhibit the strongest hereditary influence and to manifest themselves earliest in life. They are the most stable over a lifetime and the least susceptible to persuasion. That may explain why the most angry, permanent divisions in modern American politics have surrounded “God, guns, and gays” and why an intra-Republican truce on such cultural issues strikes nearly everyone as particularly fanciful. What if positions on these issues evoke the most primal responses because, in animal terms, they are most primal?
Such thinking would threaten the pieties of both left and right. Conservatives might have to adjust to a world in which few human failings could be fully blamed on cultural decline. At the same time, the liberal mind would be forced to rethink its posture toward cultural backwardness, and decide whether it ought to treat illiberal attributes like intolerance and racism as part of human nature. Would those who oppose discrimination against gays on the basis that sexuality is no choice still feel empowered to hate the right wing if they knew homophobes, too, were just born that way?
The question leads straight back, through behavior and heritability, to our DNA. In the mid-2000s, Fowler tried to isolate the effects of specific genes on civic engagement: Comparing the frequency of voting by identical twins (who share their DNA) against fraternal ones (who share half of it), Fowler and his team concluded that differentials in turnout patterns can be explained just as well by genetics as by learned behavior.